This invention relates to a semiconductor device having a barrier film for a copper (Cu) film and a method of manufacturing the same.
Recently, high integration and high speed of a semiconductor device are required. Therefore, it is necessary to reduce the width and thickness of the wiring pattern of the semiconductor device. This reduction of the wiring pattern causes an increase in the resistivity of the wiring pattern, resulting in disconnections due to electromigration. Further, the wiring pattern is exposed to a thermal process. This thermal process causes disconnections due to stressmigration. Therefore, it is desired to use wiring patterns without disconnections due to electromigration and stressmigration.
In many cases, an alloy (Al--Si--Cu alloy) containing aluminum as a main component is used as a wiring material. The resistivity of the aluminum alloy is about 3 .parallel..OMEGA.cm, and a melting point is about 650.degree. C. However, this aluminum alloy causes disconnections due to electromigration and stressmigration with high integration.
To avoid this problem, it is preferable to use a wiring material having low resistivity and a high melting point. Copper (Cu) has been proposed as a wiring material having low resistivity and a high melting point. Copper has a resistivity of about 1.67 .mu..OMEGA.cm and a melting point of 1083.degree. C. Thus, copper is superior to aluminum alloy in resistivity and melting point.
However, copper is easily oxidized and diffused. Therefore, copper wiring requires a barrier film for preventing oxidation and diffusion. A chromium nitride (CrN) film is effective as this barrier film.
A conventional manufacturing method of a semiconductor device using a CrN film is disclosed in Japanese Unexamined Patent Publication No. H3-119727 (namely, 119727/1991). As will later be described, in accordance with the conventional method, a CrN film is formed by a thermal process in a gas phase. However, the resultant CrN is a mixed crystal which is not suitable for the barrier film, since the mixed crystal comprises lattice defects. Although a single phase CrN film is desirable for the barrier film, if is difficult to form single phase CrN film using the conventional method.